Lifting device



Jan. 6, 1953" A. E." JACKSON LIFTING DEVICE 5 Sheets-Sheet 1 Filed Jan.26, 1950 INVENTOR. ALEXlS E. JACKSON ATTORNEYS A. E. JACKSON LIFTINGDEVICE Jan. 6, 1953 3 Sheets-Sheet 2 Filed Jan. 26, 1950 O n Mm Kw N mmH m A R 1 N m C. m 7 2/ x VJ M w m A A S VIA w A. W N Q Q mm ww mm %vJan. 6, 1953 A. E. JACKSON 2,624,543

LIFTING DEVICE Filed Jan. 26, 1950 5 Sheets-Sheet 3 PERCENTAGE OF F']G H6 TOTAL RANGE ASSUM ED LOAD 10 295o# 34 5200* 21% .5592 .9940 L76 5200'27 2900 34 4600 51 .5592 .0910 L60 4600 44 2900 30 4000 77 .5000 .71931.44 4040 52* 2740 25 5900 07 .4220 .6l57 1.41 3900 .01 2030 17 4400 96-2924 .4040 1.00 4350 INVENTOR,

e7 2540 10 5600 100 .1794 .3907 2.10 5500 ALEXIS E. JACKSON mezauwmeanmFIG. IIA

ATTORNEYS Patented Jan. 6, 1953 UNHTED STATES AT NT OFFICE LIFTINGDEVICE Delaware Application January 26, 1950, Serial No. 140,739

13 Claims.

This invention relates to lifting devices of the kind employed forraising automobiles and the like, and particularly this inventionrelates to such lifting apparatus of the kind wherein the lifting actionis attained by means including a pivoted lifting frame that supports theload on the free end thereof and which effects lifting movement byupward pivotal movement of such frame.

In lifting devices of the aforesaid character, the upward pivotalmovement is imparted. to the lifting frame in many different ways andthrough the uses of different sources and kinds of operating power, andit is an important object of the present invention to materially improvethe way 1 in which the operating power is applied between the pivotedlifting frame and the supporting base upon which such lifting frame ismounted. More specifically, it is an object of the present invention toso relate the power driven operating 9 means to the base and the liftingframe in such a device that the application of the lifting power is notonly accomplished in an efficient manner, but is effective in such a waythat the device is particularly convenient and safe in its operation.

The operating power is in many instances applied to lifting devices ofthe aforesaid character in the form of compressed air, and sincecompressed air in every instance will expand until a balance is attainedbetween the air pressure and the load that is being applied, it is wellrecognized that there may be instances where an excess of compressed airmay be applied so as to cause a lifting device of this kind to go beyondthe limit of movement that is desired. In this respect it should beobserved that lifting devices of the kind to which the present inventionrelates are designed and adapted in each instance for operation througha predetermined maximum lifting range, and it is important to arrangesuch lifting devices so that the load will not be inadvertently liftedbeyond such range, and to enable this to be accomplished in a simple andeffective manner is another important object of the present invention.More specifically it is an object of this invention to apply the liftingpower to the lifting frame in such a device in such a way that as thelifting frame approaches the upper limit of its normal operating range,the necessary force that must be applied to the lifting frame to supportor move the load will be suddenly increased, thereby to guard againstthe inadvertent overthrow in the operation of the lifting device.

A primary object of my invention is to afford a lifting device for raiin n and of an object such as an automobile, or the like, in a novel andexpeditious manner, and wherein the parts are so constituted andarranged that lifting of the object is accomplished efficiently and in amanner whereby the parts of the lifting device will not interfere withthe efficient work of a repairman working on the automobile, or thelike, supported on the device.

Another object of my invention is to construct a lifting device havingpivotally mounted lifting arms and a motor constituted and arrangedrelative to each other in a novel and expeditious manner whereby themotor is connected in tention to the lifting arms and is effectiveduring operation of the device to pivot the arms upwardly by pullingthereon.

A further object is to enable a novel lifting device of theaforementioned type to be constructed which embodies novel latchingdevices for positively, but releasably, holding the lifting arms of thedevice in raised position.

Yet another object of my invention is to construct a novel liftingdevice which embodies a supporting frame, lifting arms, a motor forraising the arms, and latching means for releasably holding the arms inraised position, constituted and arranged in a novel and expeditiousmanner, and which affords a novel, efii-cient, and practical liftingdevice which may be economically manufactured, and is efficient andpractical in operation.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show a preferredembodiment of the present invention and the principles thereof and whatI now consider to be the best mode in which I have contemplated applyingthese principles. Other embodiments of the invention embodying the sameor equivalent principles may be used and structural changes may be madeas desired by those skilled in the art without departing from thepresent invention and the purview of the appended claims.

In the drawings:

Fig. 1 is a longitudinal sectional view of a lifting device illustratinga preferred embodiment of my invention, the view being takensubstantially along the line Il in Fig. 2;

Fig. 2 is a top plan view of the lifting device "shown in Fig. 1';

Fig. 4 is a detail sectional view taken substantially along the line 4-4in Fig. 1;

Fig. 5 is a detail sectional view taken substantially along the line 5-5in Fig. 1;

Fig. 6 is a detail sectional view taken substantially along the line 66in Fig. 4;

Fig. '1 is a detail sectional view taken substantially along the line1--1 in Fig. 4;

Fig. 8 is a detail sectional view of the latching mechanism shown inFig. 1, showing the mechanism in a latched position;

Fig. 9 is a detail sectional view similar to Fig. 8, but showing thelatching mechanism in released position;

Fig. 10 is a detail sectional view taken substantially along the lineIll-l0 in Fig. 1;

Fig. 11 is a schematic force diagram illustrating the forces required tooperate the present lifting device in different operating positions; and

Fig. 11A is a table of values relating to the application of theoperating forces.

For the purpose of illustrating a preferred embodiment of my invention,a lifting device is shown in the accompanying drawings which comprises,in general, Figs. 1, 2 and 3, a supporting frame 22, a lifting frame 24,a motor 26, and latching mechanism 28, the motor 26 being operableduring an operation of my device to pivot the lifting frame 24 on thesupporting frame 22 from the normal, lowered position shown in solidlines in Fig. 1 to the raised position shown in broken lines therein,and the latching mechanism 23 being operable to releasably, butpositively, hold the lifting frame in such raised position, all of whichwill be discussed in greater detail presently.

The supporting frame 22, Figs. 1, 2 and 3, comprises two elongated sidebeams 3| and 32 preferably comprising two elongated, upwardly inclinedchannel members 34 and 35 having plates 3'! and 38 projecting from, andforming a longitudinal extension on the front ends thereof,respectively, and having two upwardly projecting posts 4| and 42 mountedon, and extending transversely across the rear end portions thereof. Theposts 4| and 42 each comprise an outer plate Ma and 42a and an innerplate M27 and 4227, respectively, the plates 31, 38, Ma, 42a, M1) and4212 being connected to the respective channels 34 and 35 by anysuitable means such as welding.

As is best seen in Figs. 1 and 10, the lower end portion of the posts 4|and 42 are connected together by a rod 44 which extends through sleeves48 and 49 mounted between and connected to the plates Ma and M1), and42a and 421), respectively, two wheels 46 and 41 being journaled on theopposite end portions of the rod 44 for supporting the rear end portionof the supporting frame 22. A rod 5|, similar to the rod 44, is mountedin, and interconnects, the plates 35 and 31 on the front end portion ofthe side beams 3| and 32, and two wheels 53 and 54 are journaled on theouter end portions of the rod 5| to thereby afford supports for thefront end portion of the supporting frame 22. The posts 4| and 42 arealso interconnected at their upper end portions by another rod 55, Figs.1 and 3, to thereby complete a relatively solid frame structure.

A handle 51 is mounted on the upper end portion of the posts 4| and 42,Fig. 1, and projects rearwardly therefrom to afford means for readilypushing or pulling the device 20 across a floor surface on the wheels46, 41,, 53 and 54. A tray 53 may be mounted on the handle 51 forsupporting tools and the like.

The lifting frame 24 comprises two lifting arms ti and 62 normallydisposed in substantially horizontal position between the side beams 3|and 32 of the supporting frame 22, as shown in solid lines in Fig. 1,and having the front end portions thereof interconnected by a rod 84rearwardly of the rod 5|. The other, or rear end portions of the arms 6|and 62 are welded to, or otherwise suitably secured to, a sleeve 66rotatably mounted on the rod 44 between the collars 48 and 49, Figs. 2and 10. Two axlereceiving hooks or forks 68 and 69 are mounted on thefront end portions of the arms GI and 62 of the lifting frame 24,respectively, and are secured thereto by suitable means such as welding,the hooks 68 and 69 being adapted to supportingly engage an object suchas, for example, the axle of an automobile, or the like.

In the operation of my novel device, the lifting frame 24 may be pivotedupwardly and downwardly on the rod 44 between the positions shown insolid lines and in broken lines in Fig. 1, to thereby raise and lowerthe hooks G3 and 65, and for this purpose I provide a motor such as themotor 26 which may be of any suitable type but which I prefer to be ofthe pneumatically operated type.

The motor 23 includes a cylinder 1| comprising a cylindrical-shaped sidewall 13 and two end walls 15 and 16. The end walls 15 and 16 are clampedon the side wall 13 by studs 13, Figs. 1, 3 and 5, extending through theperipheral edge portions of the end walls 15 and 16 exteriorly of theside wall 13 and held therein by nuts 19.

A cylindrical-shaped guide sleeve 8| is mounted in the central portionof the lower end wall 16 of the cylinder 1| and projects therethrough toafford a guide for the piston rod 83 of a piston 85 having a piston head86 reciprocably mounted in the cylinder 1| as will be discussed ingreater detail presently. Two bosses 88 and 89 project laterallyoutwardly from the guide sleeve 8! in opposite directions and abut thelower face of the end wall 16 of the cylinder 1|, the bosses 88 and 89being rotatably mounted on studs 01 and 99 projecting through sleeves 33and mounted in the intermediate portions of the posts 4| and 42,respectively, Figs. 3 and 1. The posts 4| and 42 are preferably inclinedforwardly from the vertical so that the studs 81 and 98 are disposedforwardly of the rod 44 for purposes which will be discussed in greaterdetail presently.

Two substantially L-shaped rods 9| and 92 extend through and are weldedto the bosses 13-8 and 59 and have one leg 94 and 95, respectively,extending through the end wall 16 on opposite sides of the guide sleeve8| and have the other legs, 91 and 98 abutting and welded to the outerface of the sleeve 8|. The upper end portions of the legs 94 and 95 ofthe rods 9| and 92 are welded to the end wall 16 of the cylinder Ti tothereby secure the rods 9| and $2 and the guide sleeve 8| in fixedposition relative thereto.

The piston head 85 comprises a substantially circular shaped flat platehaving suitable leathers ||l| mounted on the peripheral edge portionthereof by bolts I03 and nuts I04 in position to wipingly engage theinner surface of the side wall 13. The piston rod 83 comprises a rodmember I05 having one externally threaded end portion I08 extendingthrough the center of the head 86 in threaded engagement therewith andthe other end portion I09, which is also externally threaded, screwedinto a tapped opening III in a connecting 'block I I2 rotatably mountedbetween suitable spacing sleeves H and H3 on a shaft H4 extendingbetween, and connected to, the lifting arms GI and 62 between the rods44 and 64. A look nut H5 is mounted on the end I08 of the rod member I06to hold the head 86 in threaded engagement therewith.

.A sleeve member H1, forming a part of the piston 85, and having anexternally threaded end II 8 mounted in a threaded opening H9 in theblock H2, is mounted on the rod I06 in spaced relation thereto and isslidably mounted in the guide sleeve 8I, suitable packing I2I and I22 isdisposed in the opposite end portions of the guide sleeve 8| inengagement with the outer surface of the sleeve member H1. Bushings I24and I25, and cotter pins I21 and I28, Figs. 4 and 5, afford means forretaining the packing I2I and I22 in position between the sleeves SI andH1. A suitable lubricant such as, for example, grease may be packed intothe sleeve 8|, exteriorly of the sleeve I I1, between the bushings I24and I25 to afford lubrication of the sleeve I I1 during reciprocation ofthe sleeve H1 and the sleeve 82 relative to each other.

As previously mentioned, it will be seen, Fig. 4, that the rod I06 ismounted in the sleeve H1 in spaced relation to the latter. By thisconstruction, a certain amount of flexibility is imparted to the rodI06, the rod I06 being capable of movement laterally in the sleeve I I1whereby the position of the rod I06 in the sleeve I I1 may beautomatically adiusted to accommodate the piston head 86 in the cylinder13 to eliminate side thrust between the piston head 86 and the cylinder83 which might result from relatively minor irregularities inconstruction or assembly if the piston rod I06 were rigid in the sleeveI I1..

From the foregoing, it will be seen that movement of the piston 85upwardly into the cylinder H, as viewed in Fig. l, is effective throughthe connecting rod 83 to apply tension between the studs 81 and 90 onthe supporting frame 22 and the. rod H4 on the lifting frame 24 tothereby effect upward swinging movement of the lifting frame 24 aroundthe rod 44 disposed at the lower rear end portion of the supportingframe 22. Upon such movement of the lifting frame 24, the motor 26rotatestherewith on the studs 81 and 90 from the position shown in solidlines in Fig. 1 toward the position shown in broken lines therein, andit will be seen that the positioning of the studs 81 and 90 forwardly ofthe rod 44 so positions the motor 25 relative to the pivot point of thelifting frame 24 that efiicient lifting of the frame 24 is effected.

It will be seen, of course, that when it is desired to lower the liftingframe 24 from raised position, the piston 85 is moved outwardly in thecylinder II to thereby permit the frame 24 to pivot downwardly about therod 44. Thus, it will be seen that reciprocation of the piston 85 intoand out of the cylinder 1| is effective to pull the lifting frame 24into raised position and to permit the frame 24 to be lowered fromraised position, respectively.

For the purpose of reciprocating the piston 85 in the cylinder 1|, asuitable working fluid such as, for example, compressed air may be fedinto and out of the cylinder II through suitable means such as acoupling member I3I and. a

flexible hose I32, Figs. 1 and 5, the fiowof the working fluid into andout of the cylinder 1|,

6, through thehose I32, being controlled by suitable valve means, notshown.

A latching mechanism I35, Figs. 1, 2, 8 and 9; which is releasablyengageable with the legs 91 and 98 of the rods 9| and 92 is mounted onthe rod I I4 and movable with the piston to thereby afiord a releasable,positive means for latching the lifting frame 24 in raised position toim sure against accidental or unintentional lowering of the-liftingframe 24.

The latching mechanism I35 comprises two elongated plates I31 and I38pivotally mounted at one end on the rod H4 on opposite sides of theconnecting block H2 and extending toward the head 85 of the piston 85. Aplate I39 extends between, and is connected to the upper edge portionsof the plates I31 and I38 and is adapted to normally rest on the uppersurface of the piston sleeve H1, Fig. 1, to normally support thelatching plates I31 and I38 in rearwardly extending position, insubstantially parallel. alignment with the piston rod 85. A plurality ofnotches I4I, Figs. 1, 8 and 9, are formed in the lower edge portions ofeach of the, plates I31 and I38 and open toward the piston 85. The.notches I are complementary to the legs 91. and 98 of the rods 9| and92, and the legs 91 and 98 are engageable therein during movement of thepiston 85 into thev cylinder 11, the, notches. I41 each having a taperedwall I 4Ia under which, the legs 91 and 98 of the rods 9I and 92 willfreely slide during inward movement, of the piston 85, and a concavewall I4Ib which is en-.- gageable with the legs 91 and 98 of the rods 91and 92 when the latter are disposed in the slot [III to prevent outwardmovement of the Diston 85.

A release lever I43, Figs. 1, 2, 8 and 9, is embodied in the latchingmechanism I35, the release lever I43 com rising a lifting plate I45pivotally mounted between the plates I31 and I38 on a rod I41 journaledin the plates I31 and I38, and a handle I48 connected to the end of therod projecting outwardly from the plate I 31. The lifting plate I45 ismounted between the piston rod 83 and the plate I39 of the latchingmecha nism I35, and normally projects from the rod I41 toward the pistonhead 86 in substantially parallel alignment with the piston rod 83, inthe position shown in Fig. 8, the handle I48 being weighted so as totend to retain the plate I45 in that position. With the plate I45disposed in this position, it will be seen that during movement of thepiston into the cylinder H, the latching mechanism I35 slides upwardlyover the legs 9! and 98 of the rods 9I and 92 with the tapered sidewalls I4Ia of the. successive notches MI in the plates I31 and I38sliding freely over the, legs 91 and 98 of the rods BI and 92. Fullmovement of the piston 85 into the cylinder 1I disposes the rods 9I and92 in the notches I4I closest to the connecting block H2 as shownin Fig..8. Thus it will be seen that the latching mechanism is efiective topositively hold the piston 85 against accidental Withdrawal from thecylinder in any one of a plurality of positions wherein the rods 9!, and92 are latchingly engaged in notches MI in the plates I31 and I38.

When it is desired to move the piston 85 outwardly from the cylinder Hfrom a position such as that shown in Fig. 8 wherein the rods 4| and 42are disposed in notches I4I, theoper ator may, first, feed a smalladditional amount of working fluid into theeylinder 1I to thereby movethe piston 35 into the cylinder sufficiently 7" to move the taperedwalls-141A out of engagement with the legs 91 and 98 and disposethe legs91 and 98 in registration with the openings of the notches I4I, andthen, the operator may turn the handle I48 ina counterclockwisedirection,

as viewed in Fig. 8, to thereby swing the plate I45 down intocamming'engagement with the guide sleeve 8| and thereby force the platesI3! and I38 to pivot in a clockwise direction into the released positionshown in Fig. 9 wherein the plates I3! and I38 are disposed in raisedposition above the rods SI and 92, in which position the notches I4I areheld out of latching engagement with the legs 9! and 98.

Thus, it will be seen that, in the operation of my novel device, thelifting device 28 with the lifting frame 22 thereof disposed in thenormal, lowered position shown in solid lines in Fig. 1, may be moved onthe wheels 45, 47, 53 and 5:;

into position wherein the hooks 53 and 69 are a disposed below anarticle to be lifted, such as the axle of an automobile. Compressed airor the like may then be fed through the hose I32 into the cylinder II tothereby cause the piston 85 to move into the cylinder H. Movement of thepiston 85 into the cylinder H is effective to pull the lifting frame 22upwardly around the rod 44 toward the position thereof shown in brokenlines in Fig. l, to thereby raise the hooks 6B and 69 and, therefore,raise the article disposed thereon. It will be seen that, because of themanner in which the parts of my novel lifting device are constituted andarranged, a compact, practical and efficient lifting device is affordedwherein the lifting frame 22 is raised in a novel expeditious manner bythe motor 26, tension being applied to the piston 85 to thereby effectraising movement of the lifting frame.

It will be remembered that during movement of the lifting frame 22 fromthe normal position shown in solid lines in Fig. 1 toward the raise-clposition shown in broken lines therein, the motor 26 pivots on the studs31 and 90 from the solid line position toward the broken line positionshown in Fig. 1. However, it will be seen that during a completemovement of the lifting frame 22 from the lowered to raised position,the latching plates I31 and I38, remain disposed in posi tion over thepiston rod 83 so that they are urged by gravity toward the piston rod 83in all operative positions of the motor so that they are always urged bygravity toward the position in which they may latchingly engage the rodsBI and 92 when moved thereacross. Engagement of the latching mechanismI35 is effective to insure against accidental or unintentional loweringof the lifting frame 22, the latching plates I3! and I38 automaticallyriding into latching engagement with the rods 95 and 92 during movementof the piston 85 into the cylinder H. However, when it is desired tolower the lifting frame from raised position, this may readily beaccomplished by, first, feeding a small additional amount of air intothe cylinder II to thereby cause the piston 85 to move a slightlygreater distance thereinto, and, then, actuating the handle I48 tothereby lift the plates I31 and I38 out of latching engagement with therods SI and 92 and then, by permitting the air to escape from thecylinder II through the line I32, permitting the lifting frame 24 tomove downwardly.

During the downward movement of the lifting frame 24, the plate I isretained in the angular position shown in Fig. 9 to thereby hold theplates I31 and I38 out of latching engagement with the legs El! and 98of the rods SI and 92. However, as is best seen in Figs. 1, 8 and 9, anotch I45A is afforded in the top surface of the sleeve SI, adjacent theend thereof disposed closest to the connecting block H2, and is disposedin the path of travel of the free end of the plate I45 so that, as thelifting frame 24 nears its lowered position, the free edge of the plateI45 drops into the notch I45A and is stopped thereby, so that, duringthe remaining downward movement of the lifting frame 24, the plate I45is forced around toward the position shown in Fig. 8 to thereby permitthe plates I3! and I38 to drop down into operative position for engagingthe rods 9| and 92 during the next raising actuation of the liftingframe 2 5. Thus, it will be seen that after having been actuated to liftthe plates I37 and I38 out of engagement with the rods 9I and 92, theplate I45 is automatically restored to normal position during downwardmovement of the lifting frame 24 to thereby permit the plates I31 andI38 to be automatically restored to normal lowered position inpreparation for the next raising movement of the lifting, frame 24.

Under and in accordance with the present invention, the power actuatingmeans as afforded by the motor II and the piston rod 83 are associatedwith the base and the lifting frame 24 in such a way that the operationof the lifting apparatus is rendered unusually safe and advantageous inuse. Thus, it will be observed that a lifting apparatus of the kind towhich the present invention pertains is in every instance designed andintended for lifting movement throughout a predetermined range, and thatwhen the load is approaching the maximum or highest position in thisrange, it is' important that the lifting action of the mechanism becontrolled and controllable in an effective and safe manner. As shown inthe following description, and the force calculations set forth therein,such a safe mode of operation is attained under the present invention.

In respect to one factor that enters in a minor way into the calculationof the forces involved in the present structure, it will be noted thatwhere a pivoted lifting frame is utilized with upwardly extended loadengaging arms 6859, as in the present instance, that as the liftingframe pivots from a generally horizontal relation and toward its maximumangle with respect to the horizontal, the effective load that must beovercome by the operating mechanism becomes gradually less, thiseffective reduction in the involved forces being brought about by reasonof the angular relationship of the load engaging members 68 and 59 withrespect to the lifting frame. In the present embodiment of theinvention, the operating power is applied to the lifting frame at thecross shaft II4, which is located substantially midway between themounting axis 44 and the center line of the load supporting seat that isafforded in the end of each of the load engaging arms 68 and 69. Theload, of course, acts downwardly along a vertical line at all times, andthis line intersects a continuation 224, Fig. 11, of a line that isextended through the axes of the shafts 44 and IN. This point ofintersection is identified at 225 in Fig. 11, and this point ofintersection 225 in each position of the lifting frame 24 determines theeffective lever arm through which the load is applied about the mountingpivot 44.

Forillustrative purposes, the force diagram of 9 Fig. 11 has beenconstructed on the assumption that a 1500 lb. load is applied to theframe 24 at the load supporting end thereof, and the frame 24 has beenshown in six different positions, numbered as positions 1 to 6 in Fig.11. For each of these six positions, the vertical load L that iseffective at the cross shaft H4 has been computed and is shown in thetable of values that has been identified as Fig. 11A. The vertical forcethat is effective at each position of the cross shaft H4 has in eachinstance been plotted vertically as load vectors L1 to L-6, inclusive.In each instance the lower end of the load vector is located at therelated position of the shaft 1 l4, while the upper end of the loadvector constitutes the starting point of a second vector R l to Et -6,inclusive. The second vector R-l to R-fi is, in each instance, extendedparallel to the longitudinal axis of the corresponding position of thelifting frame 24 and the second vector will thus, in each instance,intersect the axis of the piston rod 83, or an extension thereof. Thispoint of intersection has been indicated in respect to the vector R-l bythe reference character l3 5-l,,and the distance betweenthe point l35-land the cross shaft H4 may then be scaled to indicate the amount ofpulling force that must be exerted by the motor H to lift or support aload of 1500 lbs. in the particular location of the lifting frame 24. Inthe table that constitutes Fig. 11A, it will be evident that in position1, as shown in Fig. 11, the pull that must be exerted is 5200 lbs.; inposition 2, 4600 lbs.; in position 3, 4000 lbs.; and in position 4, 3980lbs. In position 4, the load will have been lifted throughout asubstantial portion of the verticalrange of the present liftingapparatus, or to be exact, 87 percent of the intended maximum range, andduring this lifting movement, the amount of pressure required in thecylinder 1| will have been gradually reduced to some extent. To preventoverthrow, and insure proper control of the lifting apparatus as itmoves beyond position 4 and into the final portion of its lifting range,the present apparatus air pressure or pull in the requires an increased'7 as this final movement of operating cylinder H the lifting frame 24takes place, and it will be observed in this connection that in position5 the pull required has increased to 4400 lbs.,.while at position 6 arelatively great increase has raised the required pull to 5600 lbs.

This advantageous mode of operation is attained under the presentinvention by so relating the pivot points 44, H4 and 81 that as theangle A between the lifting frame 24 andthe base gradually increases,the included angle B between the frame 24 and the piston rod 83 isreduced rather gradually until the load has reached what may be termedthe final portion of the lifting range and so that this angle B becomesquite small and reduces quite rapidly as the load moves into and throughthis final or upper portion of the lifting range of the apparatus. Thus,in the table that forms Fig. 11A of the drawings, the included anglesbetween the frame 24 and the piston rod 83 in the several selectedposition-s of the frame 24 are indicated as angles B-l to 13-6,inclusiveand it will be observed that; these angles B do not reduce veryrapidly until the load-has entered the upper. or final portion of itsmovement.

In Fig. llthe pistonpullrequired for the assumed load in the variouspositions has been determined graphically but thismayalso be deter n d,ath matical y .since :this piston D11 Required piston pull L Thus, inFig. 11A,.the sines of the various angles B and the e'osines of theanglesA are 'set forth together with the values ofthe required pistonpull calculated according to the above formula, and while somedifferences maybe noted between the graphically and mathematicallydetermined values, this is, of course,'due to the difficulty ofdetermining the precise angular relationship of the elements.

The marked and con nued n eas in the tonpull that isgencountered thepresent apparatus when the liftingframe 24 enters the final or upperportion, of its lifting'rahge is due to the rapiddecrease in the angle13 as this final portion of the lifting stroke is entered and traversed,and in attaining such reduction in t e angle B in this portion of thestroke, the location of the pivots! to the right of thfix ffirtioalplane of the pivot 44 is important, as is the location of the pivot 81 ta d s ance above the pivptfi h eh i e t the spacin of the vots .44 anIf! other Q ds, it is important hat th p vo 01 e s 1, th when t e rame24 i ab u fill h final r pper portion .of its ift n rang t pivot .81will be spa ed but a shor di ant la e ally of the frame 24, .andtheangleB will be relati ly s l .I th s e ard. howeve t Pi .81 must in everyinstance be located a substantial distanceabove the horizontalplane ofthe pivot 44 s as to att in the require i tin a ti n on the. frame 2.4throu ho t theen r an of mov ment of theframefZA.

Fromthe foreg in it wi .b. se n ha I ha afforded a novellifting devicewherein liftingarms are moved upwardly in a novel and expeditious mannerby a motor operatin under tension, and wh reinsa wefli i nt. and prac ia peratio of the device is insured 1 v thenov l a exp d manner in whichthe parts are constituted and arranged.

Hence, .while I have illustratedand described the preferred ernbodimentsof my inventionit is to-be understood that these are'capable of.ivariation andmgdification and I therefore do ,not wish 0 b l mi d tthep fecise details set forth, but

. desiretoavailmyself of such changes and alterationsas .fallwithinth'efpurview of thefollowing claims:

Iclaim:

1. 1A lifting device comprising an elongated supporting frame, elongatedarm's pivotallymounted at oneendto said frame and having means at the-other end thereof for 'supportin'g'an object, sup- .porting means onsaid frarne'andextending' upwardly above said onee'n'd'of said arms, acylinder .pivotally mounted on said supporting means above ,saidoneendof said' arms, a" piston mounted in .said cylinder and pivotallyconnected -in tension .to said elongated arms betw'eenthe' ends thereof,said piston being movable into and out of said cylinder and operableupon movement into said cylinder to raise said"other'ends or said arms,.mearis'l projecting outwardly fr'dm said cylinder, and .a latchingmember pivotallymounted on'said piston and having .ab'utments thereonfor engaging said last named means in latching engagee the ewith dur nsuch movement or said pi ton nto-sa l nde f h din sai pi ton a ainst .mvee gi o t dly dm s d c ind r.

2. A lifting device comprising an elongated supporting frame includingupwardly extending sup porting means on one end portion thereof,elongated arms pivotally mounted at one end to said frame and havingmeans at the other end thereof for supporting an object, cylinder meanspivotally mounted on said supporting means, a piston mounted in saidcylinder means, and pivotally connected in tension to said elongatedarms between the ends thereof, said piston being movable into and out ofsaid cylinder means and operable upon movement into said cylinder meansto raise said other ends of said arms, means projecting outwardly fromsaid cylinder means, a latching member pivotally mounted between saidarms and movable into releasable latched engagement with said outwardlyprojecting means during such movement of said piston into said cylindermeans to thereby positively hold said piston against outward movementrelative to said cylinder means, and means mounted on said latchingmember and engageable with said cylinder means for moving said latchingmember from said engagement with said outwardly projectin means.

3. A lifting device comprising an elongated supporting frame comprisinga pair of upwardly inclined elongated beams disposed in spaced parallelrelation to each other, and a pair of upwardly extending posts mountedon the upper end portions of respective ones of said beams and havingupper end portions extending thereabove, elongated arms pivotallymounted at one end to said frame and having means at the other endthereof for supporting an object, a cylinder pivotally mounted on saidposts above said beams, a piston mounted in said cylinder and pivotallyconnected in tension to said elongated arms between the ends thereof,said piston being movable into and out of said cylinder and operableupon movement into said cylinder to raise said other ends of said arms,said cylinder including means projecting outwardly therefrom toward saidarms and engaged with said piston for guiding the latter, abutmentmembers projecting outwardly from said last named means transversely tosaid piston, and a latching member pivotally mounted on said piston andextending thereabove, said latching member having a plurality ofrecesses therein engageable with said abutment members during movementof said piston into said cylinder for holding said piston againstoutward movement relative thereto, and a lever carried by said latchingmember and engageable with said outwardly projecting means on saidcylinder for moving said latching member out of said latchin engagementwith said abutment members.

4. A lifting device comprising elongated supporting members, wheelsmounted on the end portions of said members for supporting the latter,an elongated lifting frame pivotally mounted at one end to one end ofsaid supporting members and having another end normally disposedadjacent to the other end of said supporting members, said other end ofsaid lifting frame having means for supporting an object, two postsmounted on and extending upwardly from said one end of said supportingmembers in spaced relation to each other, a cylinder pivotally mountedbetween said posts above said supporting members, said cylinderincluding an elongated guide member projecting outwardly therefromtoward said lifting frame and having two rods projecting laterallyoutwardly therefrom in opposite directions, an elongated piston havingone end portion extending through said guide member and slid- 12 abletherethrough into and out of said cylinder, the other end portion ofsaid piston being fixedly pivoted to said lifting frame between said twoends thereof, a latching member pivoted to said other end portion ofsaid piston and extending thereabove, said latching member having aplurality of notches therein complementary to said rods and in whichsaid rods are latchingly engageable during movement of said piston intosaid cylinder for holding said piston against outward movement relativeto said cylinder, and a lever pivotally mounted on said latching memberand manually engageable with said guide member for moving said latchingmember out of said latching engagement with said rods for freeing saidpiston for movement outwardly relative to said cylinder.

5. In a lifting apparatus, an elongated base, an elongated lifting framehaving a mounting end pivoted on a first horizontal axis disposedtransversely of said base adjacent one end of such base and said liftingframe having its other end formed with load engaging means to define aload end on said frame, said frame being shiftable about said first axisfrom a lower position wherein said frame is substantially horizontalthrough a limited lifting range'to thereby raise said load end of saidframe, means affording a second horisontal axis parallel to andsubstantially above said first axis and spaced horizontally from saidfirst axis toward the other end of said base, means affording a thirdpivotal axis disposed on and transversely of said lifting frame andintermediate the ends thereof and at a predetermined distance from saidfirst pivotal axis, power operated force applying means connectedbetween and pivoted at spaced points respectively on said second andthird axes and operable to apply lifting forces in tension between saidsecond and third axes to raise said lifting frame, said second axisbeing spaced vertically from said first axis in an amount substantiallyless than said predetermined dimension so that the included anglebetween said lifting frame and a line joining said second and third axesreduces rapidly and becomes relatively small when said frame approachesthe upper limit of said lifting range.

6. In a lifting apparatus, an elongated base, an elongated lifting framehaving a mounting end pivoted on a first horizontal axis disposedtransversely of said base adjacent one end of such base and said liftingframe having its other end formed with load engaging means to define aload end on said frame, said frame being shiftable about said axis froma lower position wherein said frame is substantially horizontal througha limited lifting range to thereby raise said load end of said frame, anoperating cylinder pivoted on a second horizontal axis parallel to andsubstantially above said first axis and spaced horizontally from saidfirst axis toward the other end of said base, a piston in said cylinder,a piston rod connected between said piston and a third pivotal axisdisposed on and transversely of said lifting frame and intermediate theends thereof and at a predetermined distance from said first pivotalaxis, said second axis being spaced vertically from said first axis inan amount substantially less than said predetermined dimension so thatthe included angle between said lifting frame and said piston decreasesrapidly and becomes relatively small when said frame approaches theupper limit of said lifting range.

7. In a lifting apparatus, an elongated base, an elongated lifting framehaving a mounting end pivoted on a first horizontal axis disposedtransversely of said base adjacent one end of such base and said liftingframe having its other end formed with load engaging means to define aload end on said frame, said frame being shiftable about said axis froma lower position wherein said frame is substantially horizontal througha limited lifting range to thereby raise said load end of said frame, anoperating piston and cylinder device including a piston, a piston rodelement and a cylinder element, one of which elements is pivoted on asecond horizontal axis parallel to and substantially above said firstaxis and spaced horizontally from said first axis toward the other endof said base, means connecting the other of said elements on a thirdpivotal axis disposed on and transversely of said liftingframe andintermediate the ends thereof and at a predetermined distance from saidfirst pivotal axis, said second axis being spaced vertically from saidfirst axis in an amount substantially. less than said predetermineddimension so that the included angle between said lifting frame and saidpiston decreases rapidly and becomes relatively small when said frameapproaches the upper limit of said lifting range.

8. A lifting device comprising an elongated supporting frame includingupwardly extending supporting means on one end portion thereof,elongated arms pivotally mounted at one end to said frame and havingmeans at the other end thereof for supporting an object, cylinder meanspivotally mounted on said supporting means, a piston mounted in saidcylinder means and pivotally connected in tension to said elongated armsbetween the ends thereof, said piston being movable into and out of saidcylinder means and operable upon movement into said cylinder mean toraise said other ends of said arms, means projecting outwardly from saidcylinder means, a latching member pivotally mounted between said armsand movable into releasable latched engagement with said outwardlyprojecting means during such movement of said piston into said cylindermeans to thereby positively hold said piston against outward movementrelative to said cylinder means, a releasing member mounted on saidlatching member and operatively engageable with said cylinder means formoving said latching member from said engagement with said outwardlyprojecting means, and means comprising an abutment on said cylindermeans and engageable with said releasing member during outward movementof said piston relative to said cylinder means for moving said releasingmember out of said operative engagement with said cylinder means.

9. A lifting device comprising an elongated supporting frame, anelongated lifting frame pivotally mounted at one end to said supportingframe and having means at the other end for supporting an object,supporting means on said supporting frame and extending upwardly abovesaid one end of aid lifting frame, a cylinder pivotally mounted on saidsupporting means above said one end of said lifting frame, said cylinderincluding an elongated guide member projecting outwardly therefromtoward said lifting frame, and an elongated piston having a headreciprocably mounted in said cylinder, and a, rod extending through saidguide member and slidable therethrough into and out of said cylinder,said rod comprising an elongated sleeve having one end portion fixedlypivoted to said lifting frame and the other end portion slidably mountedin said guide member, and an elongated rod member mounted in andslidable with said sleeve in spaced relation thereto, said rod memberhaving one end portion fixedly pivoted to said lifting frame and theother end portion connected to said head.

10. In a lifting device of the type comprising a supporting frame, anelongated lifting frame pivotally mounted at one end to said supportingframe and having means atthe other end for supporting an object,supporting means on said supporting frame and extending upwardly abovesaid one end of said lifting frame, and a cylinder pivotally mounted onsaid supporting means above said one end'of said lifting frame, melon--gated tubular guide member projecting out-- wardly from said cylindertoward said lifting: frame, bushing members mounted in oppositeends ofsaid guide member, and an elongated: piston having a head reciprocablymounted i nn said cylinder, and a rod mounted in said bush-- ingsextending through said guidemember and? slidable through saidguide-member into and out. of said cylinder, said rod comprising anelongated sleeve having one end pivotally connected to said liftingframe and the other end projecting toward said head, and an elongatedrod member laterally loosely mounted in said sleeve and reciprocabletherewith, said rod member having one end pivotally connected to saidlifting frame and the other end connected to said head for movementtherewith.

11. A lifting device comprising an elongated supporting frame, armspivotally mounted at one end to said frame and having means at the otherend for supporting an object, posts on said frame and extending upwardlyabove said one end of said arms, a cylinder pivotally mounted on saidposts on an axis located in a horizontal plane spaced above said pivotmounting of said one end of said arms and located in a vertical planeintermediate the ends of said arms, a latch member associated with saidcylinder, a piston slidably mounted in said cylinder and pivotallyconnected in tension to said arms for raising the latter around said oneend, and latch means connected to and movable with said piston andengageable with said latch member when the arms are in raised positionto lock the piston to the cylinder against accidental displacement froma position corresponding to the raised position of said arms.

12. A lifting device comprising an elongated supporting frame, anelongated lifting frame pivotally mounted at one end to said supportingframe, the other end of said lifting frame having means for supportingan object, said supporting frame including elongated supporting meansmounted on and extending upwardly from the lifting frame pivotingportion of said supporting frame, a motor pivotally mounted on saidsupporting frame above said one end of said lifting frame, the motorpivot axis being located in a vertical plane nearer said other end ofsaid lifting frame than a vertical plane passing through, the pivotalmounting of said one end of said, lifting frame, said motor including amember fixed thereto and a reciprocating member, one end of which ismovable upwardly relative to said supporting frame during an operationof said motor, said member being pivotally connected in tension to saidlifting frame between the:

ends thereof and being operable upon such move-- ment upwardly relativeto said supporting frame during operation of said motor to raise saidother end of said lifting frame, and latch means mov-- able with saidreciprocating member and en .gageable with the member fixed to the motorwhen the lifting frame is in raised position to lock said member againstaccidental displacement from a position corresponding to a raisedposition of said lifting frame.

13. A lifting device comprising an elongated supporting frame, anelongated lifting frame pivotally mounted at one end to one end of saidsupporting frame, the other end of said lifting frame being normallydisposed adjacent to the other end of said supporting frame and havingmeans thereon for supporting an object, elongated posts mounted on saidfirst mentioned end of said supporting frame and extending upwardlyfrom, and inclined toward, said other end of said supporting frame,power means including members pivotally and slidably mounted on saidposts above said one end of said supporting frame and pivotallyconnected in tension to said lifting frame between the ends thereof forapplying a predetermined tension to said lifting frame to thereby raisesaid other end of said lifting frame around said one end thereof, thepivotally mount- 16 ed power means member including a member fixedthereto, and latch means movable with said slidably mounted power meansmember and engageable with said member fixed to said pivotally mountedpower means member when the lifting frame is in raised position to lockthe slidably mounted power means member against accidental displacementfrom a position corresponding to a raised position of said liftingframe.

ALEIHS EUGENE JACKSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,552,965 Harris May 15, 1951FOREIGN PATENTS Number Country Date 299,754 Great Britain Oct. 29, 1928

